Weigh out sesame seeds, thyme, sumac, and salt.
Toast the sesame seeds. Place the sesame seeds in a cold, dry skillet over medium heat. Stir frequently until they turn golden brown and release their aroma. Remove from heat and let them cool completely.
Take ⅓ of the toasted sesame seeds and place them in a kitchen robot (food processor) or pestle and mortar. Add all the dried thyme, ground sumac, and salt. Blend or grind until powdered (around 5 min).
Add the remaining ⅔ of the sesame seeds. Mix them well in order to distribute evenly in the spice mixture.
Your Za’atar spice mix is ready! Store in an airtight container in a cool, dark, dry place. Use on bread, labneh, roasted vegetables, or meats.